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| author |   Tejun Heo <tj@kernel.org> | 2011-11-21 12:32:23 -0800 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2011-11-21 12:32:23 -0800 |
| commit | 8a32c441c1609f80e55df75422324a1151208f40 (patch) | |
| tree | 73884b06cc2db3ea155af9a88815bb5105a4473e /kernel/freezer.c | |
| parent | freezer: unexport refrigerator() and update try_to_freeze() slightly (diff) | |
| download | linux-dev-8a32c441c1609f80e55df75422324a1151208f40.tar.xz linux-dev-8a32c441c1609f80e55df75422324a1151208f40.zip | |
freezer: implement and use kthread_freezable_should_stop()
Writeback and thinkpad_acpi have been using thaw_process() to prevent
deadlock between the freezer and kthread_stop(); unfortunately, this
is inherently racy - nothing prevents freezing from happening between
thaw_process() and kthread_stop().
This patch implements kthread_freezable_should_stop() which enters
refrigerator if necessary but is guaranteed to return if
kthread_stop() is invoked. Both thaw_process() users are converted to
use the new function.
Note that this deadlock condition exists for many of freezable
kthreads. They need to be converted to use the new should_stop or
freezable workqueue.
Tested with synthetic test case.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Henrique de Moraes Holschuh <ibm-acpi@hmh.eng.br>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Oleg Nesterov <oleg@redhat.com>
Diffstat (limited to 'kernel/freezer.c')
| -rw-r--r-- | kernel/freezer.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/freezer.c b/kernel/freezer.c index 732f14f5944f..b83c30e9483a 100644 --- a/kernel/freezer.c +++ b/kernel/freezer.c @@ -9,6 +9,7 @@ #include <linux/export.h> #include <linux/syscalls.h> #include <linux/freezer.h> +#include <linux/kthread.h> /* * freezing is complete, mark current process as frozen @@ -23,7 +24,7 @@ static inline void frozen_process(void) } /* Refrigerator is place where frozen processes are stored :-). */ -bool __refrigerator(void) +bool __refrigerator(bool check_kthr_stop) { /* Hmm, should we be allowed to suspend when there are realtime processes around? */ @@ -50,7 +51,8 @@ bool __refrigerator(void) for (;;) { set_current_state(TASK_UNINTERRUPTIBLE); - if (!frozen(current)) + if (!frozen(current) || + (check_kthr_stop && kthread_should_stop())) break; was_frozen = true; schedule(); |